Gelatin dynamite composition containing sulfur



Patented Apr. 6, 1954 GELATIN DYNAMITE ,ooMi os'iTIoN CONTAINING SULFUR Walter L. Reinhart, McKeansbur'g, Pa., assignor to Atlas Powder Company, Wilmington, Del., a

corporation of Delaware No Drawing. Applicatio'iiJuly it, 1950',

Serial No. 174,579

14 Claims.

1 The present invention relates to an improvement in gelatin dynamite compositions, and, in particular, to a gelatin dynamite explosive composition especially advantageous for use in 011- Well blasting and prospecting, which explosive will not be rendered insensitive by prolongedexposure to pressure and water. It has long been known that gelatin dynamite explosives, upon the application of continued pressure, become passified or insensitive and cannot be detonated in the intended manner by commercial detonators. Such passification' is a serious detriment to the use of gelatin dynamite explosives in certain important applications, for instance in seismic prospecting.

In seismic prospecting, explosive charges are detonated at the bottoms of bore holes and from the rate and direction of propagation of the resulting shock waves, the geological structure of the given area can be constructed. Seismic prospecting is an important geological tool,- particularly in the discovery'of petroleum.

The bore holes within which theexplosives are fired are usually of great depth and filled to a considerable extent with water or drilling" mud. Commercial practice in seismic prospecting often demands that the explosive remain under this mud or water and subjected to the pressure thereof for days.- beena common experience for gelatin dynamite to become passi'fied or insensitize'd and fail to fire with commercial detonators.- While the exact reason for such passification has not been determined, it is theorized that the extended subjection of the gelatin dynamite to high water In such cases; it has- 2 tered in seismic prospecting, pelleted alkali metal nitrates are, at times, not sufficiently resistant to compression and in particular that they are not mechanically stable when exposed to water. In addition, they often do not stand up satisfactorily in storage.

It is, therefore, an object of the present invention to provide an explosive composition having improved resistance to pressure and water.

A further object is the formulation of a gelatin dynamite which will retain, after long storage, its ability to detonate when subjected to high water pressures.

A further object of the invention is to provide agelatin dynamite explosive having improved utility for seismic prospecting.

Other objects of the invention will be apparent from aconsid'eration of the following specification and claims.

According to the invention, a gelatin dynamite explosive composition having improved resistance to high water pressures and increased stability in storage is provided by including in the gelatin dynamite composition comprising the usual ingredients thereof, a substantial portion of pelleted interio'rly ca'vitated elemental sul-.

phur. By including pelleted interiorly cavitated elemental sulphur in the gelatindynamite, explosives may be obtained which exhibit markedly superior propagation-sustaining properties under high water pressure, in comparison with compositions hitherto employed. To illustrate this, the following general comparison may be made (for a more detailed comparison see the tables of specific examples):

Explosive Head Time Results Ordinary gelatin dynamite; 200 ft.-87 p. s. i

2 hrs. N0 detonation in ials.

Gelatin cynamite contain- 300 it.=l30p. s.i 24 hrs..- Do.

ing pelleted NaNOa,

Gelatin dynamite accord- .500 ft.=2l5 p. s.i 9 days. Detonation in all ing to invention. cases.

pressures renders the air particles; normally'dis tributed throughout the composition, inoperative as propagation-sustaining media.

Normally gelatin-dynamite explosives'have had included in their composition cork, bag'asse' pulp, and the like in anattempt to offset this passifying effect. However; this has not in general been effective in retaining the sensitivity of the explosive under high water pressures for more than a few hours. in U. S. Patent No. 1,77 8-,7-18 'that thisproblem might be solved by the use ofhollow pellets of alkali metalnitrates as ingredientsofthe-explosive mix. Experience has indicated; how ever, that under the severe-conditions encoun- Ithas been suggested" to about 7% nitrocotton, usually from about 0.4% to about the amount of nitrocotton being sufficient to provide a viscous liquid or a gel of the desired consistency with the nitroglycerine as is standard practice. The particular proportions of nitroglycerine to nitrocotton selected will depend, as is well known; upon the amount of solid ingredients included in the 'explosive. When substantial amounts of solid ingredients are present the proportion of nitrocotton to nitroglycerine may be such as to provide a more or less viscous liquid, the adsorption and absorption of the solid ingredients being relied upon to render the mixture plastic. As the proportion of nitrocotton to nitroglycerine is increased the mixture becomes more viscous until a gel isobtained, and this gel may be relied upon to render the composition plastic. At any rate the amounts and proportions of nitroglycerine and of nitrocotton, as well as any solid ingredients, will be selected in accordance with common practice to provide a plastic, solid mass.

If sodium nitrate is employed, it will generally be present in an amount from about 3% to about 65%, While fuels will usually be between about 3% and about 25%. In accordance with conventional practice the proportions of fuel and of sodium nitrate, when used, may be varied to provide a desirable oxygen. balance in the explosive. If ammonium nitrate is used, it may be present in an amount from about 2.0% to about 50%, depending upon the particular grade of ammonia gelatin dynamite desired.

The nitroglycerine used in the present compositions may be relatively pure nitroglycerine or it may be a nitrated mixture of glycerine, ethylene glycol and corn or sugar or other nitratable substances, as is usually employed in the :art. The aforesaid nitrated mixture, as well as relatively pure nitroglycerine, is designated in the trade as nitroglycerine and that term is used herein to include both materials.

By pelleted sulphur is meant small interiorly cavitated (hollow) pellets or beads of elemental sulphur the interiors of which are air-filled. Such pellets can be obtained by spraying molten sulphur into air in fine droplets with subsequent solidification or freezing of the droplets in flight. While the size of the sulphur pellets employed in the composition of the invention may vary over a wide range, the pellets are usually smaller than a U. S. S. No. 6 screen aperture and larger than a U. S. S. No. 80 screen apering the hollow sulphur pellets. Preferably, this is accomplished by providing the sulphur pellets in the composition with an exterior coating of a water-resistant film-forming substance, for ex ample, a coating of wax or of a resinous material of the type hereinafter described. Such a coating appears to seal off the pores of the sulphur and increase the resistance of the resulting composition to water pressure. Preferably, a microcrystalline hydrocarbon Wax or a convertible urea reaction product, for example, a convertible urea-formaldehyde reaction product ineluding dimethylolurea, a convertible urea-melture. Preferably, they are smaller than a U. S. S. H

No. 14 screen aperture and larger than, a U. S. S. No. 45 screen aperture. pellets larger than those which will pass through a U. S. S. No. 6 screen tend to break upon handling or milling. To the extent that such breakage occurs, the advantages of the invention are not realized. This tendency to breakis not found in the smaller particles, but, when the pellet size is less than that which will be retained on a U. S. S. No. 80 screen, the pellets tend to be ineifective to prevent pressure passification.

The quantity of pelleted sulphur present in the novel composition may vary widely depending upon the particular conditions of use to which the explosive is intended but generally the pelleted sulphur will be present in an amount from about 5% to about 50% by weight, preferably from about 10% to about 45% by weight.

It has been found that improved results are obtained when the composition contains a material which serves to prevent water from enter- It has been found that v amine reaction product or a convertible ureamelamine-formaldehyde reaction product is employed, to provide the water resistant coating although other film-forming materials may be used if desired. In the event a convertible material is employed, conventional curing catalysts, for example, an ammonium salt, such as ammonium chloride, may be employed to facilitate the conversion of the reaction product into the insoluble state, but even in the absence of a catalyst, the convertible urea reaction product will be converted as cured with the passage of time. The amount of coating material added may vary, but generally from about 0.5% to about 5.0% will be used, and the preferable range is from about 1.0% to about 3.0% by weight of the sulphur.

To prevent the pellets from sticking or agglomerating when treated with wax, a coating of clay may be applied following the treatment with the wax. If used, the amount of clay will depend on the amount of wax used and may comprise from about 1% to 3% by weight of the sulphur. In place of coating the sulphur pellets, prevention of water-penetration into the sulphur pellets may be accomplished by adding a convertible reaction product of the stated type to the dry dope used in preparing the composition, as hereinafter described.

To aid in preventing the deterioration of the compositions on storage, a stabilizer is preferably added. For this function, organic amines are preferred, in particular urea, carbazole and diphenylamine. While the amount of stabilizer added to the composition will vary with the particular composition and the length of time and conditions of storage (especially temperature), in general from about 0.5% to about 5.0% may be employed.

The pelleted sulphur used in the present invention may, as stated above, be prepared by blowing molten sulphur upwardly through a nozzle into the atmosphere. For best results, it is desirable that the temperature of the sulphur as it leaves the nozzle be as near to the crystallizing temperature as possible. After the pellets have formed, they are gathered and classifled according to size.

If desired, pelleted sulphur of the desired size may then be provided with the water-resistant coating, for example, the wax or wax and clay, or the resin. This may be accomplished, for example, by adding the molten wax to a quantity of pellets in a heated paddle type mixer and mixing until a uniform coating is obtained. If a clay coat is also desired, the clay may then be added and mixing continued until the clay coat is evenly distributed.

If the pelleted sulphur is to be provided with a coating of resinous material, the material providing the resin, in finely divided form in suspension or slightly moistened or rendered slightly sticky by heating or in solution, may be mixed with the pelleted sulphur in a suitable mixing device. A particularly advantageous way of applying a resin coating to the sulphur pellets is as a suspension or partial solution in water. The pellets thus treated can be dried to provide the water resistant coating. In the event a thermosetting resin is employed the pellets may be heated to convert the resin coating to the insoluble state. A convenient method of applying a coating on the pellets is to suspend or partially dissolve the convertible reaction product in cool water containing a conversion catalyst such as about of ammonium chloride based on the dry weight of the reaction product, and to apply the resulting liquid to the pellets which have been heated to an elevated temperature, for'example to about 150 F. The heat contained in the pellets is suiiicient to dry'the coating and to convert the reaction product into an insoluble resin coating. Alternatively, the material providing the resin, in dry finely divided condition, may be mixed with the other dry ingredients to form a dry dope and it will be found that the resin will be distributed through the mixture and will serve to prevent water-penetration into the interior of the sulphur pellets.

The pelleted sulphur, desired, is then added to coated or 'uncoated, as the secondary ingredients, as, for example, sodium nitrate or ammo- Q nium nitrate, wood pulp. pit meal. corn flour, stabilizer, etc, to form a dry dope which in turn is worked into the nitric ester base (which is prepared according to standard practice) until the desired consistency is obtained. It may then be packed into cardboard cartridges which may be sealed by crimping in the usual manner.

To test the explosive effect of the novel mixtures, the following conventional procedure may be followed:

A charge, preferably two cartridges 2" in diameter and 14%; long, together with an electric ca are loaded end to end into a steel bomb 3" in diameter and about 40 long, the cap leads being arranged for detonating the bomb. When two or more cartridges are employed they are preferably joined together with a cardboard sleeve to assure proper alignment and end to end contact. The bomb is then filled with water under the desired pressure and kept at that pressure, by the addition of water to compensate for that absorbed by the explosivev composition, for the desired time. It is then sealed oif and, while still at the desired pressure, taken to a bombproof structure for firing.

To determine whether the explosive composition propagates completely through the full length of the column, use is, made of three lead crusher cylinders about '2" in diameter by 4" in length. The cylinders are each placed on a steel base plate under the bombs in an upright position and on a straight line on 12" centers and the explosive composition lies directly above them. To prevent their deformation when the bomb shatters, a steel cap plate about 1" thick and 3" square is interposed between each of the cylinders and the bomb. In this manner, the transmitted compression effect is recorded on each lead block. Complete or partial failures are shown by uncompressed or very slightly compressed lead cylinders. The bomb'is detonated andthe linear compression of the, lead cylinders measured and. then converted into, percent compression.

nitrate, respectively. Composition 2 contains In Table III, compositions compQSitions while comcompositions of the in- 6 Seisnon-pelleted sulphur. 1, 3 and 5 are prior art positions 2, 4 and .6 are vention. All tests were made with a. N0. mograph Electric Blasting Cap.

Table I Nitr0g1ycerine Nitr0cott0n. Sulphur 36. 6. Burnt IO-mesh, retained on 35-mesh) 1.0 Ground sodium nitrate Coarse sodium nitrate 35. 7 agasse 4.1

alk 1.0

Hydrostatic Pressure tests:

Pressure in ft., H20. Time (hrs) Percent Compression:

1 Non-pelleted sulphur passing through a U. S. S. No. 14 and re tamed on a. U. S. S. No. 35 screen.

2 Pclleted sodium nitrate coated with 2% wax and passing through a U. S. S. No. 14 and retained on a U. S. S. No. 35 screen.

3 Pcllcted sulphur interiorly cavitated passing through a U. S. S. N0. 14 and retained on a U. S. S. No. 35 screen.

4 Pelleted sulphur interiorly cavitated passing through a. U. S. S. N o. 8 and retained on a U. S. S. No. 20 screen.

Table II' Nitroglycerinc Nitrocotton Pelleted sulphur interiorly cavitated Ground sodium niate sure tests:

Pressure in it,

H2O Time (hrs.). Percent compres- 1 Passing through a U. S. S. No. 14 and retained'on a, U. S. S. No. 35 screen and coated with 2% of a microcrystalline hydrocarbon wax.

2 Passing through a U. S. S. N o. 8 screen and retained on a U; S. S. No. 14 screen.

3 Passing through a U. S. S. N o. 20 screen and retained on a U. S. S. No. screen.

4 Passing through a U. S. S. N o. 14 and retained on a No. 35 screen and coated with 2% of a microcrystalline hydrocarbon wax. and with an exterior coating of finely divided clay.

5 Passing through a U. S. S. N o. 14 and retained on a U'. S: S1No. 35 screen and coated with 2% of a partially polymerized reaction product of urea and formaldehyde (Cascamite-a watei soluble ureaiormaldehyde resin adhesive in dry powder form).

2, 4, 7: 8 T Table III about 20% and 80% and nitrocotton in an amount between about 0.3% and about 7%, and containing from about 5% to about 50% by Weight of hollow sulphur pellets, said hollow sulphur pellets being smaller in size than a No. 6

gitroglytgerine. l roco on Ground Sodium mtme U. S. S. screen aperture and larger than a U. S S. g fifi nitratem I No. 80 screen aperture and containing a reaction p p Come Apricot Pit Meal product of formaldehyde and at least one com Fine Apricot Pit Meal p nd selected from the group consisting of g Flour urea and melamine.

rea .0 Pu1verizedSu1phur A gelatm dynam1te explosive as claime in 3 x 3 5 35 e claim 4 wherein said reaction product is provided ohnik I I as a coating for the sulphur pellets and is a urea- Hydrostatic Pressure f ld h d resin Tests.

Pressureinit, 1120.- 6. A gelatin dynamite explosive comprising nitroglycerine in an amount between about pression.

Lead No.1 and about 80% and nitrocotton in an amount figg 1 1%.-

11 between about 0.3% and about 7%, and containing from about 5% to about 50% of hollow sul- 20 phur pellets and from about 0.5% to about 5.0%

Passing through a U. S. S. No. 14 and retained on a U. S. S.

lgllgkglgzfifixirgdeidzggivgglgigfl ogffialgicgogiigggigge hydrocarbon of a stabilizing organic amine, Said sulphur pel- 1 Passing through a U. S. S No. 14 End retained o n a U. S. S. lets bem'g smaller 1n S128 than U S- S 6 No. 35 screen and coated with 2% of apartially polymerized reaction screen aperture and larger than a. U. S. S. No. 80 product of urea and formaldehyde (Oascamite"). Screen aperture Table IV 7. A gelatin dynamite explosive comprising nitroglycerine in an amount between about 20% 1 2 and about 80% and nitrocotton in an amount between about 0.3% and about 7%, and containing from about 5% to about 50% by weight of Ntrcglyce'rme 1:: &3 &3 hollow sulphur pellets, said hollow sulphur pelg-g 8-? lets being smaller in size than a U. S. S. No. 6 1 screen aperture and larger than a U. S. S. No. 80 screen aperture and having a wax coating com- 1 j prising from about 0.5% to about 5.0% by weight 23 of the sulphur; and from about 0.5% to 5.0% of n arsllil'i'frlin'e' fiisl a Sta l zi an c am egggjz gf 20 2 9 8. A gelatin dynamite explosive composition ig' comprising nitroglycerine in an amount between Q 6 3% about 20% and about 80% and nitrocotton in an 0 22 40 amount between about 0.3% and about 7%, and containing from about 5% to about by 1 Passing through a u. s. s. No. 14 and retained on a U. s. s. No. weight of hollow sulphur pellets, said hollow sul- 35 screen and coated with 2% of a partially polymerized reaction phur pellets being Smaller in Size than a No. 6

product of urea and formaldehyde (Cascamite). U S S Screen aperture and larger than a U S s As will be apparent to those skilled in the art, 5 No. 80 screen aperture and containing a reaction compositions according to the invention are susproduct of formaldehyde and at least one comceptible of considerable variations in ingredients pound selected from the group consisting of urea and percentages without departing from the feaand melamine present in an amount from about tures of the invention. 0.5% to about 5.0% by weight of the sulphur, I claim: 50 and containing from about 0.5% to about 5% of 1. A gelatine dynamite explosive composition a stabilizing organic amine. comprising nitroglycerine in an amount between 9. A gelatin dynamite explosive composition about 20% and about 80%, and nitrocotton in an comprising nitroglycerine in an amount between amount between about 0.3% and about 7%, and about 20% and about 80% and nitrocotton in an containing from about 5% to about 50% of holamount between about 0.3% and about 7%, and low sulphur pellets, said hollow sulphur pellets containing from about 10% to about 45% by being smaller in size than a U. S. S. No. 6 screen weight of hollow sulphur pellets, said hollow aperture and larger than a U. S. S. No. 80 screen sulphur pellets being smaller in size than a aperture. U. S. S. No. 14 screen aperture and larger than 2. A gelatin dynamite explosive composition a U. S. S. No. 45 screen aperture and having a comprising nitroglycerine in an amount between wax coating comprising from about, 1 0-% to about a about and nitrocotton in an about 3.0% by weight of the sulphur; and from amount between about 0.3% and about 7%, and about 95% t about 5 f a Stabilizing organic containing from about 5% to about 50% by amine weight of hollow sulphur pellets, said hollow sul- 5 10 A i a gelatin dynamite explosive comprising P 3 g fi a nitroglycerine in an amount between about 20% p61 g a and about 80% and nitrocotton in an amount be- No. 80 screen aperture and having a wax coating -om ri n from 0.5 to 5 b Wei ht of the g g if g y g from about 10% to about 4.5% by weight of hol- A gelatin dynamite explosive as claimed in low sulphur pellets, said hollow sulphur pellets claim 2 wherein the ax coated ulphur ellets Smaller in Size than a: U- S. S. No. Screen are also coated it c1a,y aperture and larger than a U. S. S. No. 45 screen 4. A gelatin dynamite explosive composition aperture and ha a coating comprising a comprising nitroglycerine in an amount between action product of urea and formaldehyde present tween about 0.3% and about 7% and containing 14. The explosive of claim 7 wherein said sta- 0 bilizing organic amine is urea.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Perry Nov. 19, 1918 Bacon et a1 May 17, 1921 Stoops Oct. 27, 1931 Seil May 24, 1932 Stratton Sept. 27, 1932 Jones Mar. 2, 1937 Tapley Sept. 27, 1938 

1. A GELATINE DYNAMITE EXPLOSIVE COMPOSITION COMPRISING NITROGLYCERINE IN AN AMOUNT BETWEEN ABOUT 20% AND ABOUT 80%, AND INTROCOTTON IN AN AMOUNT BETWEEN ABOUT 0.3% AND ABOUT 7%, AND CONTAINING FROM ABOUT 5% TO ABOUT 50% OF HOLLOW SULPHUR PELLETS, SAID HOLLOW SULPHUR PELLETS BEING SMALLER IN SIZE THAN A U. S. S. NO. 6 SCREEN APERTURE AND LARGER THAN A U. S. S. NO. 80 SCREEN APERTURE. 